Display apparatus

1. A display apparatus comprising: a memory; and a processor that executes instructions stored in the memory, wherein the processor (a) detects a horizontal start position, a horizontal end position, a vertical start position, and a vertical end position of an effective image area of an input analog image signal, (b) calculates a first difference that represents a difference between the detected horizontal start position of the input analog image signal and a horizontal start position of an effective image area of a candidate format, (c) calculates a second difference that represents a difference between the detected horizontal end position of the input analog image signal and a horizontal end position of the effective image area of the candidate format, (d) calculates a third difference that represents a difference between the detected vertical start position of the input analog image signal and a vertical start position of the effective image area of the candidate format, (e) calculates a fourth difference that represents a difference between the detected vertical end position of the input analog image signal and a vertical end position of the effective image area of the candidate format, (f) determines whether the calculated first difference and the calculated second difference satisfy a first predetermined condition, (g) determines whether the calculated third difference and the calculated fourth difference satisfy a second predetermined condition, (h) determines the candidate format as a format of the input analog image signal if the calculated first difference and the calculated second difference satisfy the first predetermined condition and the calculated third difference and the calculated fourth difference satisfy the second predetermined condition, (i) calculates a fourth value for each of candidate formats, by dividing a product of a first value and a second value by a third value, if the first predetermined condition or the second predetermined condition is not satisfied, wherein the first value represents a horizontal resolution of a candidate format, the second value represents a vertical resolution of a candidate format, and the third value represents a total number of horizontal dots of a candidate format, and (j) determines one of the candidate formats as a format of the input analog image signal, based on the fourth values calculated for the candidate formats, if the first predetermined condition or the second predetermined condition is not satisfied.

2. The display apparatus according to claim 1 , wherein the first predetermined condition is satisfied if the calculated first difference and the calculated second difference are equal to each other or if a difference between the calculated first difference and the calculated second difference falls within a threshold value, and the second predetermined condition is satisfied if the calculated third difference and the calculated fourth difference are equal to each other or if a difference between the calculated third difference and the calculated fourth difference falls within a threshold value.

3. A method comprising: detecting a horizontal start position, a horizontal end position, a vertical start position, and a vertical end position of an effective image area of an input analog image signal; calculating a first difference that represents a difference between the detected horizontal start position of the input analog image signal and a horizontal start position of an effective image area of a candidate format; calculating a second difference that represents a difference between the detected horizontal end position of the input analog image signal and a horizontal end position of the effective age area of the candidate format, calculating a third difference that represents a difference between the detected vertical start position of the input analog image signal and a vertical start position of the effective image area of the candidate format; calculating a fourth difference that represents a difference between the detected vertical end position of the input analog image signal and a vertical end position of the effective image area of the candidate format; determining whether the calculated first difference and the calculated second difference satisfy a first predetermined condition; determining whether the calculated third difference and the calculated fourth difference satisfy a second predetermined condition; determining the candidate format as a format of the input analog image signal if the calculated first difference and the calculated second difference satisfy the first predetermined condition and the calculated third difference and the calculated fourth difference satisfy the second predetermined condition; calculating a fourth value for each of candidate formats, by dividing a product of a first value and a second value by a third value, if the first predetermined condition or the second predetermined condition is not satisfied, wherein the first value represents a horizontal resolution of a candidate format, the second value represents a vertical resolution of a candidate format, and the third value represents a total number of horizontal dots of a candidate format; and determining one of the candidate formats as a format of the input analog image signal, based on the fourth values calculated for the candidate formats, if the first predetermined condition or the second predetermined condition is not satisfied.

4. The method according to claim 3 , wherein the first predetermined condition is satisfied if the calculated first difference and the calculated second difference are equal to each other or if a difference between the calculated first difference and the calculated second difference falls within a threshold value, and the second predetermined condition is satisfied if the calculated third difference and the calculated fourth difference are equal to each other or if a difference between the calculated third difference and the calculated fourth difference falls within a threshold value.

5. A non-transitory storage medium that stores a program causing a computer to execute a method, the method comprising: detecting a horizontal start position, a horizontal end position, a vertical start position, and a vertical end position of an effective image area of an input analog image signal; calculating a first difference that represents a difference between the detected horizontal start position of the input analog image signal and a horizontal start position of an effective image area of a candidate format; calculating a second difference that represents a difference between the detected horizontal end position of the input analog image signal and a horizontal end position of the effective image area of the candidate format; calculating a third difference that represents a difference between the detected vertical start position of the input analog image signal and a vertical start position of the effective image area of the candidate format; calculating a fourth difference that represents a difference between the detected vertical end position of the input analog image signal and a vertical end position of the effective image area of the candidate format; determining whether the calculated first difference and the calculated second difference satisfy a first predetermined condition; determining whether the calculated third difference and the calculated fourth difference satisfy a second predetermined condition; determining the candidate format as a format of the input analog image signal if the calculated first difference and the calculated second difference satisfy the first predetermined condition and the calculated third difference and the calculated fourth difference satisfy the second predetermined condition; calculating a fourth value for each of candidate formats, by dividing a product of a first value and a second value by a third value, if the first predetermined condition or the second predetermined condition is not satisfied, wherein the first value represents a horizontal resolution of a candidate format, the second value represents a vertical resolution of a candidate format, and the third value represents a total number of horizontal dots of a candidate format; and determining one of the candidate formats as a format of the input analog image signal, based on the fourth values calculated for the candidate formats, if the first predetermined condition or the second predetermined condition is not satisfied.

6. The display apparatus according to claim 1 , further comprising a conversion unit that converts the input analog video signal to a digital signal using a sampling clock frequency specified by the candidate format, when the candidate format is determined as the format of the input analog image signal.

7. The display apparatus according to claim 1 , wherein the display apparatus includes a projector.

8. The display apparatus according to claim 1 , wherein the display apparatus includes a liquid crystal display.

9. The method according to claim 3 , further comprising converting the input analog video signal to a digital signal using a sampling clock frequency specified by the candidate format, when the candidate format is determined as the format of the input analog image signal.

10. The method according to claim 3 , wherein the method is implemented in a display apparatus including a projector.

11. The method according to claim 3 , wherein the method is implemented in a display apparatus including a liquid crystal display.